Digital signatures are valid substitutes to traditional inked signatures in many countries. Digital signatures, like inked signatures, may be used as evidence to show that a particular body of data was signed.
Typical digital signatures allow a signer to electronically sign data and be reasonably certain that the data will not change. Thus, data having a digital signature is locked; it cannot be altered without invalidating the digital signature. Because of this, a digital signature can be used as evidence to show that the data locked by the digital signature was signed and has not been altered since it was signed.
While the data may not change since it was signed, how the data is presented can change with some types of electronic documents. Data presented in one way may be substantially different to the viewer than when presented in another. Important data can be shown with a large font that is easily seen in one presentation, for instance, but in another be shown in a small-font footnote.
This can be a significant problem for types of digital signatures that do not preserve the view of the data when signed. These types of digital signatures will not show how the data was presented when signed, making them less reliable evidence. Thus, while digital signatures typically lock the data that is signed, some types of digital signatures do not lock or preserve the view of the data when it was signed.
Some other types of digital signatures, however, preserve the view of the data when it was signed using a link to the view at a remote website. Here the data of the digital signature can be presented in other ways after the data is signed, but the view seen by the signer is preserved, at least initially, through this remote website.
These digital signatures suffer from significant drawbacks. First, the view stored in the remote website may not be valid or exist when the digital signature is later used as evidence. In many real-world situations, a digital signature may need to be used as evidence ten, twenty, or even thirty years from when it was signed. The view initially preserved at the remote website may not exist then. Second, the view, even if it exists, may not be readily available, such as when the remote website cannot be readily accessed.
Another type of digital signature partially addresses this drawback but it suffers from another problem. This type of digital signature combines the view of the data when signed and the data itself. But combining the data and the view prevents the data from being read by a machine. Because the data is not machine readable, it cannot be repurposed, which significantly limits the usefulness of this type of digital signature.
Given the foregoing, there is a need in the art for a digital signature that can permit signed data to be repurposed and that can also include the view when signed.